They demonstrate a hole double quantum dot in an un­doped gallium-arsenide/aluminum-gallium-arsenide (GaAs/AlGaAs) heterostructure. The device shows good charge stability and negligible hysteresis with respect to gate voltage. The interdot coupling can be tuned over a wide range, controlling the transition from a large single dot to two well-isolated quantum dots. Using charge sensing, they show that the dot can be completely emptied of holes and operated in the few-hole regime.

The device should provide a means for future experiments focusing on manipulating single hole spins in single and double gallium-arsenide quantum dots.

(a) Scanning electron micrograph (SEM) of partially processed device, showing titanium-gold (Ti/Au) gates on gallium-arsenide/aluminum-gallium-arsenide (GaAs/AlGaAs) heterostructure surface used to form a quantum dot and QPC charge sensor. The yellow dotted line indicates the location of the cross section sketch shown in panel (b). (b) Sketch of cross section of left half of the device.

Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.